This invention relates generally to diagnostic processes for rotating machinery and more particularly concerns a system which "cleans electronic diagnostic signals by separating such signals into component signals representing independent contributions from individual sources of the overall signal.
In many applications, the performance of rotating machinery must be monitored for diagnostic purposes. This is typically accomplished using a sensor which produces a diagnostic signal representing an operating characteristic of the machine. For instance, it is often desirable to monitor a specific vibration level within an aircraft engine, but a diagnostic sensor cannot be properly positioned inside of the engine because it would tend to interfere with engine operation. A diagnostic sensor is thus typically mounted in a non-invasive fashion to the outer casing of the engine. However, since the sensor mounted to the casing is sensitive not only to the vibrations of interest but to many other vibrations occurring in the engine as well, the diagnostic signal produced by the sensor becomes a "composite" signal having contributions from all of the sensed vibration sources. Thus, analyzing the diagnostic signals from a non-invasively mounted sensor is often rendered difficult or even impossible because they can become highly contaminated by secondary sources.
Some conventional diagnostic analyzing systems use time averaging methods to eliminate random noise from diagnostic signals. Frequency domain post processing techniques such as cepstrum analysis are also used in some of the most advanced systems. However, these methods are complex, require time consuming frequency domain processing, and are limited in their ability to separate random and periodic signals from different sources.
Thus, there exists a need for a system and method for processing diagnostic signals which can quickly separate a "composite" diagnostic signal into the component signals representative of the contribution from independent sources and thus "clean-up" the desired signal.